BOTANY 



flowered Gentiana germanica occur, and an especially characteristic plant 

 having its headquarters in the county is the calamint (Calamintha parui- 

 folia or Nepeta), which is locally very abundant on the dry banks in the 

 neighbourhood of West Wycombe, Chalfont St. Peter's, Seer Green, etc. 

 The maple and holly are plentiful in the hedgerows, and the buckthorn 

 (Rhamnus catbarticus) , the wayfaring tree (Viburnum Lanfana), the true 

 cherry (Prunus Cerasus), as well as P. avium, occur. 



THE READING BEDS are the lowest members of the Tertiary strata 

 found in Buckinghamshire : they consist very largely of stiff clay mottled 

 with a great variety of colours, but they also include beds of sharp sand, 

 also variously coloured, and loams. They rest unconformably on the 

 Chalk, and once formed an unbroken sheet over its whole area, but they 

 have been largely removed by denudation ; the various outliers such as 

 those at Penn however testify to the much wider range they formerly 

 had. The Reading Beds now occupy a considerable surface of southern 

 Bucks about Wooburn, Burnham, Beaconsfield, Hedgerley, Chalfont St. 

 Peter's and Denham. 



The varied soils formed by these beds necessarily give rise to a 

 diversified flora, and it is rendered even more interesting from the 

 extensive deposits of drift gravels by which in many places they are 

 covered. Therefore in quick succession we find purely ericetal species 

 such as the trailing St. John's wort (Hypericutn bumifusum) and bird's-foot 

 (Ornithopus perpusillus), and clay-loving species such as Mentha rubra and 

 M. piperita. 



Where the drift gravels are common we then find a most 

 interesting series, such as the silvery cinquefoil (Potentilla argentea), the 

 subterranean clover (Trifolium subterraneum) , the soft clover (T. striatum) 

 and the hare's-foot (7". arvense), the buck's-horn plantain (Plantago 

 Coronopus), the tower-cress (Arabis perfoliata), the climbing bindweed 

 (Polygonum dumetorurn)^ the cress (Lepidium heterophyllumvzr. canescens), the 

 hawkweeds H. boreale^ H. sciaphilum and H. umbellatum, the saw-wort 

 (Serratula tinctoria), the Deptford pink (Diantbus Armeria), the broom- 

 rape (Orobancbe Rapum-genlstce) ^ the pearl-wort (Sagina ciliata) and very 

 locally S. subulata. The less pervious clays have afforded the sedges 

 Carex sfrigosa, C. e/afa, and chamomile (A nthemisnobilis) . 



THE LONDON CLAY is another Eocene formation, and it is found 

 resting on the Reading Beds as a stiff brownish clay, often containing 

 large nodules of calcareous matter called septaria, but is usually very 

 uniform in its character throughout its whole thickness, which is not less 

 than 300 feet in some places. It occupies a large tract of country 

 between Slough, Langley and Drayton, where it is extensively excavated 

 for brickmaking, and Stoke Common, Fulmer, Red Hill are also situated 

 on it, while there are extensive outliers capping the Chalk, as at Lane 

 End, which is 593 feet in altitude, and the neighbouring eminence of 

 Priests is 606 feet above sea level. 



Like the Reading Beds, this formation is often covered with drift 

 gravels, and then we see in close proximity the ericetal and glareal 



39 



